Java Software Engineer, Shipping Calculation Platform Group - EC Logistics Development Department (ECLD)

Job Description:

Business Overview

When people think of Rakuten, they often think of services such as Rakuten Ichiba, Rakuten Books, and Rakuten Fashion. Behind the order is a sophisticated logistics platform that manages inventory, fulfillment, shipping, delivery tracking, and customer notifications.

The EC Logistics Development Department builds and operates the mission-critical systems that power these logistics services. Every package delivered to a customer depends on the reliability and performance of the platforms we develop.

Department Overview

The EC Logistics Development Department develops and operates the systems that support Rakuten’s logistics ecosystem.

Our systems power warehouse operations across Japan, enabling inventory management, receiving, shipping, fulfillment, delivery scheduling, shipment tracking, and customer notifications. We also support Rakuten Super Logistics (RSL), providing logistics services for Rakuten merchants and helping them deliver products efficiently to customers.

Our platforms are business-critical. If our systems become unavailable, warehouse operations stop and customer deliveries are impacted. As a result, reliability, scalability, and operational excellence are at the core of everything we build.

As a software engineer on our team, you’ll solve challenging distributed systems problems while building highly available backend services that support millions of customers and merchants across Rakuten’s e-commerce platform.

Our mission is to transform logistics through technology by delivering fast, reliable, and seamless shopping experiences.

We strive to:

・Deliver the right product to the right customer, at the right place and time.

・Build reliable logistics platforms that provide exceptional customer experiences.

・Enable merchants to grow their businesses through efficient logistics services.

・Continuously innovate and expand Rakuten’s logistics platform.

We are looking for a passionate Java Software Engineer to build high-performance, scalable backend systems powering Rakuten’s logistics platform.

You’ll work on large-scale distributed systems responsible for critical business operations while collaborating closely with platform engineers, architects, product managers, and operations teams.

This role offers opportunities to solve complex engineering challenges involving scalability, reliability, performance optimization, cloud infrastructure, and system architecture.

Position:

Why We Hire

We're expanding our team to meet the growing demands of our innovative projects and to further strengthen our commitment to delivering exceptional solutions to our customers.

Position Details

You’ll have the opportunity to:

・Build mission-critical systems that directly support one of Japan’s largest e-commerce platforms.

・Design and develop highly scalable backend services.

・Solve challenging distributed systems and performance problems.

・Work with modern cloud-native technologies.

・Influence technical design and architecture.

・Collaborate with experienced engineers across multiple platform teams.

・Take ownership of services from design through production operations.

<Responsibilities>

・Design, develop, and maintain scalable backend services using Java.

・Design reliable and highly available distributed systems.

・Improve system performance, scalability, and operational efficiency.

・Collaborate with platform and framework teams to improve developer productivity.

・Participate in architecture discussions and technical design reviews.

・Monitor production systems and contribute to incident response and continuous improvement.

・Write clean, maintainable, well-tested production code.

・Contribute to engineering best practices.

Mandatory Qualifications:

<Backend Development>

・More than 6 years of professional Java development experience.

・Deep expertise in Java, Micronaut, and modern backend development.

・Proven track record designing and delivering production-grade RESTful APIs and/or gRPC services (Protocol Buffers).

・Proven experience designing, building, and operating microservice architectures at scale.

<Distributed Systems>

・Proven production experience designing event-driven systems with Kafka, including partitioning strategies, consumer group management, and failure handling.

・Deep experience building and operating scalable, highly available distributed systems.

・Hands-on production experience with reactive programming (Reactor, RxJava, etc.).

・Experience diagnosing and resolving distributed systems failures in production.

<Infrastructure>

・Production experience deploying, scaling, and operating services on Kubernetes.

・Experience developing cloud-native applications on Kubernetes and private cloud platforms; AWS exposure is a plus.

・Experience with CI/CD pipelines and Git.

・Experience with capacity planning and performance tuning at scale.

<Architecture & Design>

・Strong understanding of software architecture principles and design patterns.

・Experience leading technical design reviews and making architectural decisions.

<Data>

・Deep experience with relational and NoSQL databases (MySQL, Oracle, or Couchbase), including query optimization, schema design, and performance tuning.

・Experience with Redis for caching and session management.

<Development Environment>

・Java

・Kotlin (Gradle scripts and tooling)

・Micronaut

・Kubernetes

・Docker

・Kafka

・gRPC / Protocol Buffers

・REST APIs

・MySQL / Oracle / Couchbase

・Redis

・Gradle

・Git

・CI/CD (Jenkins)

・Elastic / Kibana

Desired Qualifications:

・Experience working in Agile/Scrum teams.

・Experience with monitoring and observability tools such as Elastic/Kibana, Prometheus, or Grafana.

・Experience working on large-scale, high-traffic, mission-critical backend systems.

・Experience working in a globally distributed engineering team.

・Comfort working with AI-powered developer tools (coding assistants, internal chatbots, etc.).

・Excellent problem-solving and communication skills.

Other Information:

Additional information on Location

Rakuten Crimson House (Head office)

Additional information on English Qualification

Proficient in English

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